Though a well-known hymn tells us we should love “all creatures great and small,” loving some of the smaller creatures on Earth – particularly the creepy-crawly kind – can prove a little challenging. So many of us have a fear of spiders, for example, that it sits in the top 10 list of phobias worldwide. But maybe this Spotlight will evoke a little warmth toward the beasts; we look at the surprising ways in which spiders and some other creepy critters may benefit human health.
Mary Astell – a 17th century English philosopher – once said: “None of God’s creatures absolutely consider’d are in their own nature contemptible; the meanest fly, the poorest insect has its use and vertue.” And it seems this may be true in relation to the medical world.
Take the common housefly. They feed on decaying organic matter – such as garbage and feces – and as a result, carry over 100 potentially life-threatening pathogens that can be transmitted to humans. Based on this information, it is no wonder many of us take the opportunity to swat the little pests when they come into close range.
But you may be surprised to learn that the common housefly could actually help scientists learn more about human illnesses. In a study published in the journal Genome Biology in October 2014, Dr. Jeff Scott and colleagues from Cornell University in Ithaca, NY, revealed how they sequenced the genome of the housefly using DNA from six female flies.
Comparing the DNA of the housefly with that of the fruit fly – which shares almost 60% of human genes – the team identified genes that make houseflies immune to the pathogens they carry, potentially bringing us closer to new treatments for human illnesses.
“The housefly genome provides a rich resource for enabling work on innovative methods of insect control, for understanding the mechanisms of insecticide resistance, genetic adaptation to high pathogen loads, host parasitoid interactions, and for exploring the basic biology of this important pest,” the authors explained.
And this discovery is only the tip of the iceberg; there are many more equally as unpleasant critters that may offer benefits for human health.
Many of you are likely to be cringing at the sight of the word “spider.” Millions of us hate the eight-legged monstrosities, running away at the speed of light when one randomly appears from under the sofa. But whatever your thoughts about these arachnids, there is no doubt they are amazing creatures.
There are believed to be at least 40,000 species of spiders worldwide, residing on every continent except Antarctica.
Though all spiders have the ability to bite, only around a dozen can cause harm to humans with their toxic venom. Black Widows, Brown Recluse spiders and Hobo spiders are some of the venomous spiders found in the US. A bite from one of these can cause symptoms such as fever, itching or rash, nausea and vomiting, high blood pressure and breathing difficulties. Only very rarely can a spider bite lead to death.
But while spider venom can cause human harm, it may also aid human health. Earlier this month, Medical News Today reported on a study conducted by researchers from The University of Queensland in Australia, who claimed to have identified compounds in spider venom that could help treat chronic pain in humans.
From screening the venoms of 205 species of spider, they discovered that 40% of venoms contained at least one compound that has the ability to block a pathway involved in chronic pain in humans, called Nav1.7. One particular compound that showed promise – called Hd1a – was identified in a species of spider called Haplopelma doriae – a member of the tarantula family.
Study leader Prof. Glenn King believes the findings may lead to more effective treatments for the millions of people worldwide who suffer from chronic pain. “Untapping this natural source of new medicines brings a distinct hope of accelerating the development of a new class of painkillers that can help people who suffer from chronic pain that cannot be treated with current treatment options,” he adds.
And it is not only spiders’ venom that could aid progress in human medicine. Spider silk – the protein fiber that the creatures use to make their webs – may be useful for treating nerve damage in humans, according to a 2011 study by researchers from Hannover Medical School in Germany.
Spider silk is an extremely durable fiber, with one study claiming it is five times stronger than steel. The Hannover researchers believe its high durability makes spider silk a promising candidate for reconstructive nerve surgery, with the technique already proving successful in animal models.
Compared with spiders, we tend to have a higher tolerance for bees. Though they seem incapable of finding their way back out of an open window they just flew through – making us do a lot of curtain-flapping and arm-waving – they are responsible for producing one of the nation’s most-loved foods: honey.
But according to scientists, these insects are capable of so much more. In 2013, MNT reported on a study published in Antiviral Therapy, in which researchers revealed how a toxin found in bee venom – melittin – has the potential to destroy human immunodeficiency virus (HIV).
The investigators, from the Washington University School of Medicine, explained that melittin is able to make holes in the protective, double-layered membrane that surrounds the HIV virus. Delivering high levels of the toxin to the virus via nanoparticles could be an effective way to kill it.
Study author Dr. Joshua L. Hood believes these findings could lead to the creation of a vaginal gel to halt HIV transmission. “Our hope is that in places where HIV is running rampant, people could use this gel as a preventive measure to stop the initial infection,” he explained.
A more recent study published in September 2014 claims bees may also be useful for creating a new class of antibiotics. Researchers from the Lund University in Sweden discovered lactic acid bacteria in fresh honey found in the stomachs of bees that has antimicrobial properties.
The team found that the bacteria is effective against a number of drug-resistant pathogens responsible for potentially life-threatening infections, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE).
At a time when existing antibiotics are increasingly failing to work against such infections, the researchers say their findings suggest a viable alternative.
Like spiders, scorpions are creepy but fascinating. There are around 90 species of scorpions living in the US, most likely to be found in rocky and sandy areas.
All scorpions are venomous, though only 25-30 species possess a venom that is toxic enough to cause severe illness in humans.
A person who is unlucky enough to be stung by one of these more deadly species may experience difficulty breathing, muscle spasms, high blood pressure, a rise or reduction in heart rate and irregular heartbeat. But while their venom can cause heart problems, you may be surprised to learn that it could also treat them.
A 2011 study by researchers from the University of Wisconsin-Madison School of Medicine and Public Health found that compounds in the venom of the African Emperor scorpion, or Pandinus imperator, may be effective for the treatment of heart failure.
The researchers found that the compounds, called calcins, activate the release of calcium in human heart cells, allowing better heart muscle contraction – something that is limited in patients with heart failure.
Another study published in 2010 identified a compound in the venom of the Central American bark scorpion – a species commonly kept as a pet – that could stop heart bypasses from failing.
The study researchers – from the University of Leeds in the UK – explain that the compound, called margatoxin, could prevent neointimal hyperplasia following heart bypass surgery – a common complication that causes blood vessel blockage. Margatoxin works by blocking a potassium ion channel called Kv1.3, which is involved in neointimal hyperplasia.
“These results look promising, but we won’t know if this approach will benefit patients undergoing bypass surgery until more research is undertaken in patients to establish its long-term efficacy and safety,” commented Prof. Peter Weissberg, medical director at the British Heart Foundation, adding:
“This is a good example of a substance that is dangerous in its natural form – a scorpion sting, having potential medicinal benefits if used appropriately.”
Of all the creatures featured in this Spotlight, frogs are probably one of the least feared, but they are certainly one of the most interesting. They have the ability to jump more than 20 times their body length, and some species – such as the Budgett’s frog – have camouflage capabilities.
There are more than 6,000 species of frogs worldwide, of which 90 reside in the US. While many species of frog are venomous, very few cause harm to humans. In fact, some species of frog could aid humans in the fight against cancer.
In 2011, MNT reported on a study by researchers from Queen’s University Belfast in Northern Ireland that revealed the discovery of two proteins in the skin of the Waxy Monkey Frog and the Giant Firebellied Toad that can disrupt angiogenesis, or new blood vessel growth.
The researchers explain that cancer tumors develop their own blood supply, fueling themselves with oxygen and nutrients to help them grow. A protein that can switch off blood vessel growth means tumors would be unable to fuel themselves, meaning they would stop growing. “Stopping the blood vessels from growing will make the tumor less likely to spread and may eventually kill it. This has the potential to transform cancer from a terminal illness into a chronic condition,” says study author Prof. Chris Shaw.
On the other hand, Prof. Shaw says such a protein could be used to activate blood vessel growth, which could treat a number of conditions in which rapid blood vessel repair is required, such as blood vessel damage following stroke.
Some of you may not have heard of the Gila monster. Found in southwestern US and northwestern Mexico, it is the only venomous lizard in the US, and one of only a few venomous lizards worldwide. Rest easy, though; a bite from this beast is not fatal to healthy adults. But its saliva could be a lifesaver.
In 2007, a study by researchers from the University of North Carolina at Chapel Hill School of Medicine revealed how exenatide – a synthetic form of a compound found in the saliva of the Gila monster, called exendin-4 – may help people with diabetes control their condition and lose weight.
The compound works by causing the pancreas to produce more insulin when blood sugar is too high. In the study, 46% of patients who were given exenatide in combination with diabetes drug metformin had good control of their blood sugar, compared with only 13% of control participants.
“The Gila monster only eats three or four times a year, and a compound produced in its salivary glands called exendin-4 may help them digest these meals very slowly over time. That is an advantageous quality when translated into controlling diabetes,” commented Dr. Michael Trautmann of pharmaceutical company Eli Lilly – who helped develop the drug.
The Gila monster is not the only reptile that could help treat diabetes. A 2012 study published in Nature Communications found toxins in snake venom that could be beneficial for the condition, and they could even help treat high blood pressure and cancer.
The team analyzed gene sequences from the Burmese python and garter snake to reach their findings. They found that – although the venoms of these snakes can be harmful to humans – the toxins in them can be changed into harmless molecules that could make effective drugs.
“The venom gland of snakes appears to be a melting pot for evolving new functions for molecules, some of which are retained in venom for killing prey, while others go on to serve new functions in other tissues in the body,” said lead author Dr. Nicholas Casewell, from the Liverpool School of Tropical Medicine in the UK.
It seems that what Mary Astell said is not far from the truth; even “the meanest fly” or “the poorest insect” has its uses.